Gas-engine.



B. F. STEWART.

GAS ENGINE.

APPLICATION IILED JULY 11, 1910.

Patented Aug". 13, 1912.

Iii/(Euler BENJAMIN I. STEWART, or CHICAGO, ILLmoIs.

GAS-ENGINE.

Specification of Letters Patent.

Patented Aug. 13, 1912.

Original application filed September 11,1907, Serial No. 392,340. Divided. and this application filed July 11, 1910. 'Serial No. 571,526.

. 1'0 all whom it may concern Be it known that I, BENJAMIN F. S'rnw- Ana, acitizen of the United States,and resident of Chicago, county of Cook, and State of Illinois, have invented-certain new and useful Improvements in Gas-Engines, of which the following is a specification, and which are illustrated in the accompanying drawings, forming a part thereof,

Thisa plication isa division of my application ed Sept. 11, 1907, Serial No.

The invention relates to the twocycle type or to any ;(gas engine in which provision is made for eveloplng a ressure in front of l the piston on its out stro (e.

The objects of the invention are to increase the efficiency of the engine on high speed and to provide means for cooling the piston. a

The invention consists in the structure hereinafter described and which is illustrated in the accompanying drawings, in which: I

Figure 1 is a transverse vertical section of port 16, so located in the cylinder walls that it will be uncovered by the piston when at the end of its instroke. A transfer passage is shown at 17 as bein cored in the walls of the cylinderand lea in from the chamber of the crank case to t e induction port 19, a screen 18 being located within this passage. The exhaust port is shown at 20, and an igniting device at 21. The instroke of the piston produces a partial vacuum in the crank case when the induction port 16 is uncovered. Upon the outstroke of the piston the charge thus admitted into the crank case is compressed until the port 19 is uncovered, when it is instantl transferred to the inner end of the cylin er. The next instroke of the piston again reduces the pressure within the crank case below cated above the pivot 22. This partition'is provided with a small aperture 24, through which the vapors may enter as the compression takes place in the crank case.- The inrushing vapors lmpinge on the lnner surface of the wall 25 constituting the piston face, and reduce its temperature. U on the instroke, as partial vacuum is pr uced in the crank case the vapors pass out through the aperture 24. By this means there is a con- :stant change of vapor within the piston chamber and consequently a constant transfer of heat from the piston face. The aperture 24 is comparatively small, thereby insuring a rapid movement of the vapors and '75 causing the entire inflow to sweep the wall 25. When the engine has attained considerable speed the movement of its piston becomes so rapid that but a comparatively small quantity of the vapor within its chamber can be discharged on the in stroke, hence the pressure within this chamber does not fall as low as the pressure within the crank case. As a result the cubic contents of the compression chamber, consisting of the crank case and the adjacent end-of the cylinder, becomes effectively reduced. The volume of the charge admitted through the port 16 is slightly increased because of the increase of mlnus pressure in the crank case and smaller percentage of the vapors in the chamber of the piston escaping through the aperture24. A smaller percentage of the new charge is admitted to the piston chamber partly because this chamber is already well filled and par ly because'of the small size ,of the aperture and the rapid movement of the piston. As, therefore, the speed of the engine increases its charge increases in volume and the compression becomes higher. The cooling action, however, is not lessened because at high speeds the velocity of so much of thevapors as actually enter the piston chamber is increased and the wall 25 is more effectively swept by them.

' While but a single aperture 24 is shown in the recess passes the induction port 19 as v the piston approaches theend of its outstroke. The wall'28 of this recess, which extends practically longitudinally of the cylinder, is inclined toward the cylinder wall, thereby the recess 27 is given a more contracted throat. This wall 28 deflects the incoming charge upwardly and forward,

and by reason of the contracted throat of the recess the expulsion from it of all the burned gases by the inrushing charge is secured. The sparking device 21 is so located that itpractically projects into this recess when the piston reaches the end of its instroke. Thus the resence of uncontaminatedv explosive mixture adjacent to the sparking device is assured. The inclination of the wall of the piston face up to the outer end of the wall 28 reduces thecubic contents of the clearance or compression space and provides for the draina e toward the exhaust pipe of any oi-ls w ich may accumulate upon the piston face, andthese' oils are kept comparatively cool by the cool ing arrangement for the piston hereinbefore described, thereby lessemng the deposit of carbon on the piston face by the burning of the oil.

I claim as my invention-- 1. In a gas engine, in combination, a cylinder, av closed crank case open to the cylinder, a duct leading from the crank case to the upper portion of the cylinder, a hollow trunk piston reciprocable' within the cylin vder, a partition crossing the chamber of the 'port for transferring vapor from the crank case to the cylinder, and a hollow piston reciprocating in the cylinder and having a.

ported transverse partition, the port being of such size that at normal speeds the pressure within the piston chamber will remain higher than in the crank case during the instroke.

BENJAMIN F. STEWART.

Witnesses:

Louis K. 'GILLSON, E. M. KLATCHER. 

